This application relates to a scroll compressor having a motor protector incorporated into the compressor at a location remote from the motor, and further having structure for enhancing the flow of refrigerant across the protector in the event of a high discharge pressure condition.
Scroll compressors are becoming widely utilized in refrigerant compressor applications. As known, a scroll compressor includes two scroll members each having a base and a generally spiral wrap extending from the base. The wraps interfit to define compression chambers. One of the two scroll members is caused to orbit relative to the other, and as the two orbit the size of the compression chambers decrease, compressing an entrapped refrigerant.
There are many design challenges in the use of scroll compressors. One design challenge occurs when there is a loss of charge in the refrigerant cycle. In such situations, the pressure ratio of the discharge pressure to suction pressure increases greatly. This results in additional heat, and is detrimental to the operation of the compressor, and the entire refrigerant system. It is desirable to sense such a condition as quickly as possible and stop operation of the compressor.
Modern compressors are typically powered by an electric motor. The electric motor is provided with a motor protector which stops operation of the motor should anyone of a number of conditions be sensed. One particular condition is excess heat in the compressor housing which is sensed by the motor protector. In addition, anomalies in the electric current or voltage being supplied to the motor will also cause the protector to stop operation.
Recently, the Assignee in the above-referenced invention has invented the concept of locating the motor protector at a location remote from the motor. In this way, the protector can sense the occurrence of high temperature causing conditions more rapidly, and thus can stop the compressor more rapidly. U.S. patent application Ser. No. 09/527,428 entitled xe2x80x9cMotor Protector on Non-Orbiting Scrollxe2x80x9d and filed on Mar. 16, 2000 is disclosed in the base of the non-orbiting scroll. While this location is quite beneficial, it would be desirable to increase the efficiency of this motor protector identifying the improper conditions and stopping operation of the motor.
In disclosed embodiments of this invention, a scroll compressor is provided with a motor protector located at a location remote from the motor. Further, valving is preferably provided to identify conditions indicative of an outdoor fan failure, and in particular, high pressure differentials. When such conditions are identified, discharge pressure refrigerant is allowed to flow over the motor protector. Under outdoor fan failure or blocked fan conditions, the discharge refrigerant will be hotter than normal. The motor protector will promptly stop operation of the motor. More broadly, the invention could be said to include a number of ways of providing increased sensitivity to conditions indicative of the outdoor fan failure at the motor protector.
Again, in preferred embodiments, a relief valve which is open when the discharge to suction pressure differential exceeds a predetermined value, is positioned to allow discharge refrigerant to pass over the protector when opened. In embodiments, this valve may be located in the base of the non-orbiting scroll, may be located in a protective cover on the non-orbiting scroll, or may be located in an outer suction passage leading to the beginning of the compression chambers in the non-orbiting scroll. In this latter embodiment, the motor protector is further located in this outer suction area. With this embodiment, no additional height is required for either the motor protector or the relief valve.
In a further embodiment, a heat sink is provided both above and below the motor protector. As the discharge refrigerant passes over this heat sink, heat is taken away from the motor protector. However, in a loss of charge situation the volume flow of this refrigerant will decrease. Further, the refrigerant will typically have a higher temperature. Thus, the heat transfer from this heat sink will also decrease. The motor protector will thus increase in temperature, and soon trips and stop operation of the motor.
These and other features of this invention can be understood from the following specification and drawings, the following of which is a brief description.